Hi Perlmonks,

I have made a perl module DNAappend.pm with a single subroutine DNAappend in order to learn the steps of making a module. Then I have written a small script i.e. joindna.pl. When I have tried to run the perl script, the command window does not show the expected result. I can't make out where I have made the mistake in the script. I know it could be a very silly question to the perl monks but I am at my wit's end to find the solution. I welcome any constructive suggestions from the perlmonks about the script and perl module.

Here goes the script joindna.pl

#!/usr/bin/perl
use warnings;
use strict;
use DNAappend;
  my $a='ATGC';
  my $b='TTTT';
print"\n\n";
  print DNAappend($a,$b);
print"\n\n"; 
exit;
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I have written the DNAappend.pm as follows:

package DNAappend;
use strict;
use warnings;

sub DNAappend {
  my ($head,$tail)=@_;
  return ($head.$tail)
  }
1;
[download]

The command window has shown the result:

 C:\Users\x\Desktop>joindna.pl

Undefined subroutine &main::Dnaappend called at C:\Users\x\Desktop\joi
+ndna.pl line 8.

C:\Users\x\Desktop> 
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The correct result should look like: